Regioselective Introduction of Indolin-3-one Moieties to Substituted Heteroaromatic Compounds.

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• C2-substituted indolin-3-ones are valuable heterocyclic compounds.
• Existing synthetic methods may lack efficiency or broad applicability.

Purpose of the Study:

• To develop a mild and efficient dual catalytic method for synthesizing C2-substituted indolin-3-ones.
• To explore the scope and selectivity of the generated C-acylimine intermediate.
• To demonstrate the utility of this method for late-stage functionalization of biomolecules.

Main Methods:

• A dual catalytic system was employed to generate a reactive C-acylimine species in situ.
• The C-acylimine intermediate was intercepted by various nucleophilic arenes.
• Competition experiments were conducted to assess the selectivity of the C-acylimine.
• The method was applied to functionalize melatonin, protected amino acids, and dipeptides.

Main Results:

• The dual catalytic method successfully formed C2-substituted indolin-3-ones under mild conditions.
• The C-acylimine intermediate demonstrated regioselective trapping by arenes, even when the most reactive site was blocked.
• Pyrrole was identified as a preferred heteroaromatic trap over other tested heterocycles.
• Late-stage functionalization of melatonin, amino acids, and dipeptides was achieved, showcasing the method's potential.

Conclusions:

• A novel and mild dual catalytic strategy for C2-substituted indolin-3-one synthesis has been established.
• The C-acylimine intermediate exhibits useful reactivity and selectivity profiles.
• This methodology offers a valuable tool for the late-stage diversification of complex biomolecules.